Tissue resection procedures, such as colonoscopy and polypectomy, are carried out by inserting introduction sheaths, such as endoscopes or laparoscopes, into the body of a patient through incisions or natural anatomical openings (e.g., oral, vaginal, and/or anal cavities). Commonly, such devices employ snares, typically designed as loops, for performing tissue resection procedures. An operator tightens the snare around the stalk (peduncle) or other tissue, thus removing it.
In a typical resection procedure, such as endoscopic mucosal resection (EMR), the submucosal layer is injected with saline to lift the mucosal layer forming a bleb. The bleb facilitates access to and visualization of the lesion. The bleb may also create a protective barrier over the muscularis layer. However, the formation of the bleb may make snaring more difficult as it increases tension in the mucosa surrounding the lesion. Further, the geometry and volume of the bleb varies based on techniques used, insertion material properties, injection speed, and lesion morphology. It may therefore be difficult to control the bleb boundaries, which can exacerbate snaring difficulties. Furthermore, snares have a tendency to slip off targeted tissue (bleb), and often require repeated efforts to capture the tissue before the resection procedures can be successfully performed.
Various methods have been developed to improve the functioning of snares. For example, one common approach is to apply a downward force on the snare in an effort to improve traction between the snare and the unwanted tissue. This downward force is usually limited due to a lack of stiffness in the snare loop, and may cause the distal end of the snare loop to deflect away from the tissue. In order to control this deflection, the downward force may continue to be applied and/or increased until the tissue is snared. Continued or increased applied force increases vulnerability of surrounding tissues towards accidental damage, as well as increases the time required to complete a procedure. In addition, it may be sometimes difficult to apply the necessary downward forces due to geometric and physical limitations such as the geometric shape of the bleb.
Therefore, there exists a need in the art for an improved snare with better capabilities, thereby allowing consistent capture, excision, and/or removal of unwanted tissue.